U.S. patent number 7,000,589 [Application Number 10/868,205] was granted by the patent office on 2006-02-21 for determining manifold pressure based on engine torque control.
This patent grant is currently assigned to General Motors Corporation. Invention is credited to Michael Livshiz, Gregory P. Matthews.
United States Patent |
7,000,589 |
Matthews , et al. |
February 21, 2006 |
Determining manifold pressure based on engine torque control
Abstract
A torque control system for an engine includes a throttle plate
having an adjustable throttle position to regulate a first mass air
flow into the engine. A control module determines a first mass air
flow into the engine and monitors an engine speed. The control
module calculates a volumetric efficiency of the engine based on
the first mass air flow and the engine speed and calculates the
desired MAP based on the volumetric efficiency.
Inventors: |
Matthews; Gregory P. (West
Bloomfield, MI), Livshiz; Michael (Ann Arbor, MI) |
Assignee: |
General Motors Corporation
(Detroit, MI)
|
Family
ID: |
35459212 |
Appl.
No.: |
10/868,205 |
Filed: |
June 15, 2004 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20050274357 A1 |
Dec 15, 2005 |
|
Current U.S.
Class: |
123/350; 123/361;
123/399; 123/480; 701/104; 73/114.37 |
Current CPC
Class: |
F02D
9/02 (20130101); F02D 11/105 (20130101); F02D
41/32 (20130101); F02D 13/0219 (20130101); F02D
41/0072 (20130101); F02D 41/18 (20130101); F02D
2041/001 (20130101); F02D 2200/0411 (20130101); F02D
2250/18 (20130101); F02M 26/05 (20160201) |
Current International
Class: |
F02D
41/18 (20060101) |
Field of
Search: |
;123/350,361,399,480,488
;73/118.1,118.2 ;701/104,114-115 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Huynh; Hai
Attorney, Agent or Firm: DeVries; Christopher
Claims
What is claimed is:
1. A torque control system for an engine, comprising: a throttle
plate having an adjustable throttle position to regulate a first
mass air flow into said engine; and a control module that
determines a first mass air flow into said engine, that monitors an
engine speed, that calculates a volumetric efficiency of said
engine based on said first mass air flow and said engine speed and
that calculates said desired MAP based on said volumetric
efficiency.
2. The torque control system of claim 1 wherein said volumetric
efficiency is further based on calibration coefficients.
3. The torque control system of claim 2 wherein said calibration
coefficients are determined based on said engine speed and said
first mass air flow.
4. The torque control system of claim 1 further comprising an inlet
cam shaft that regulates air flow into a cylinder of said engine,
wherein said volumetric efficiency is further based on a phase
angle of said inlet cam shaft.
5. The torque control system of claim 1 further comprising an
exhaust cam shaft that regulates an exhaust flow from a cylinder of
said engine, wherein said volumetric efficiency is further based on
a phase angle of said outlet cam shaft.
6. The torque control system of claim 1 wherein said desired MAP is
further based on said first mass air flow.
7. The torque control system of claim 6 wherein said desired MAP is
further based on a temperature of said first mass air flow.
8. The torque control system of claim 6 further comprising an
exhaust gas recirculation (EGR) system that regulates a second mass
air flow into said engine, wherein said desired MAP is further
determined based on said second mass air flow.
9. A method of determining a desired manifold absolute pressure
(MAP) based on an engine torque request of an engine, comprising:
determining a first mass air flow into said engine; monitoring an
engine speed; calculating a volumetric efficiency of said engine
based on said first mass air flow and said engine speed; and
calculating said desired MAP based on said volumetric
efficiency.
10. The method of claim 9 wherein said volumetric efficiency is
further based on calibration coefficients.
11. The method of claim 10 wherein said calibration coefficients
are determined based on said engine speed and said first mass air
flow.
12. The method of claim 9 wherein said volumetric efficiency is
further based on a phase angle of an inlet cam shaft.
13. The method of claim 9 wherein said volumetric efficiency is
further based on a phase angle of an outlet cam shaft.
14. The method of claim 9 wherein said desired MAP is further based
on said first mass air flow.
15. The method of claim 14 wherein said desired MAP is further
based on a temperature of said first mass air flow.
16. The method of claim 14 wherein said desired MAP is further
determined based on a second mass air flow into said engine via an
exhaust gas recirculation (EGR) system.
17. A method of determining a throttle position, comprising:
determining a first mass air flow into said engine; monitoring an
engine speed; calculating a volumetric efficiency of said engine
based on said first mass air flow and said engine speed;
calculating said desired MAP based on said volumetric efficiency;
and calculating said throttle position based on said desired
MAP.
18. The method of claim 17 wherein said volumetric efficiency is
further based on calibration coefficients.
19. The method of claim 18 wherein said calibration coefficients
are determined based on said engine speed and said first mass air
flow.
20. The method of claim 18 wherein said volumetric efficiency is
further based on a phase angle of an inlet cam shaft.
21. The method of claim 18 wherein said volumetric efficiency is
further based on a phase angle of an outlet cam shaft.
22. The method of claim 17 further comprising: generating an engine
torque request; and determining said first mass of air based on
said engine torque request.
23. The method of claim 22 wherein said desired MAP is further
based on said first mass of air.
24. The method of claim 23 wherein said desired MAP is further
based on a temperature of said first mass of air.
25. The method of claim 23 wherein said desired MAP is further
determined based on a second mass of air flowing provided by an
exhaust gas recirculation (EGR) system.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is related to U.S. Application Serial No.
10/868,192, filed Jun. 15, 2004, entitled, "Determining Manifold
Pressure Based on Engine Torque Control". The disclosure of the
above application is incorporated herein by reference.
FIELD OF THE INVENTION
The present invention relates to engine torque control, and more
particularly to determining manifold pressure based on engine
torque control.
BACKGROUND OF THE INVENTION
Internal combustion engine control systems have been developed as
steady-state, torque-based control systems. In a torque-based
control system, the desired torque output of the engine is
indicated by a driver input. More specifically, a driver adjusts a
position of an accelerator pedal, which provides an engine torque
request. The throttle is controlled to regulate air flow into the
engine that provides the desired engine torque output.
Torque-based control systems determine the mass of air needed to
produce the desired engine torque and determine throttle position,
exhaust gas recirculation (EGR) valve position and cam phase angles
based on the mass of air. Traditionally, the throttle position is
commanded directly as a function of the accelerator pedal position.
Commonly assigned U.S. patent application Ser. No. 10/664,172,
filed on Sep. 17, 2003 and entitled Engine Torque Control with
Desired State Estimation describes a method which uses the manifold
filling dynamics and can initially command the throttle to a value
greater than the steady-state value. As the manifold fills with air
the, throttle is brought back to the steady-state position. This
results in an a more aggressive partial throttle acceleration, but
may lead to an unexpected feel of the vehicle to the driver by not
producing the expected behavior of the throttle to a step-in change
in the accelerator pedal.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a torque control system
for an engine. The torque control system includes a throttle plate
having an adjustable throttle position to regulate a first mass air
flow into the engine. A control module determines a first mass air
flow into the engine and monitors an engine speed. The control
module calculates a volumetric efficiency of the engine based on
the first mass air flow and the engine speed and calculates the
desired MAP based on the volumetric efficiency.
In other features, the volumetric efficiency is further based on
calibration coefficients. The calibration coefficients are
determined based on the engine speed and the first mass air
flow.
In another feature, the torque control system further includes an
inlet cam shaft that regulates air flow into a cylinder of the
engine. The volumetric efficiency is further based on a phase angle
of the inlet cam shaft.
In another feature, the torque control system further includes an
exhaust cam shaft that regulates an exhaust flow from a cylinder of
the engine. The volumetric efficiency is further based on a phase
angle of the outlet cam shaft.
In still other features, the desired MAP is further based on the
first mass air flow. The desired MAP is further based on a
temperature of the first mass air flow.
In yet another feature, the torque control system further includes
an exhaust gas recirculation (EGR) system that regulates a second
mass air flow into the engine. The desired MAP is further
determined based on the second mass air flow.
Further areas of applicability of the present invention will become
apparent from the detailed description provided hereinafter. It
should be understood that the detailed description and specific
examples, while indicating the preferred embodiment of the
invention, are intended for purposes of illustration only and are
not intended to limit the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the
detailed description and the accompanying drawings, wherein:
FIG. 1 is a schematic illustration of an exemplary engine system
that is operated based on the engine torque control system
according to the present invention; and
FIG. 2 is a flowchart illustrating steps performed by the engine
torque control system of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following description of the preferred embodiment is merely
exemplary in nature and is in no way intended to limit the
invention, its application, or uses. For purposes of clarity, the
same reference numbers will be used in the drawings to identify
similar elements. As used herein, the term module refers to an
application specific integrated circuit (ASIC), an electronic
circuit, a processor (shared, dedicated, or group) and memory that
execute one or more software or firmware programs, a combinational
logic circuit, or other suitable components that provide the
described functionality.
Referring now to FIG. 1, an engine system 10 includes an engine 12
that combusts an air and fuel mixture to produce drive torque. Air
is drawn into an intake manifold 14 through a throttle 16. The
throttle 16 regulates mass air flow into the intake manifold 14.
Air within the intake manifold 14 is distributed into cylinders 18.
Although a single cylinder 18 is illustrated, it is appreciated
that the engine torque control system of the present invention can
be implemented in engines having a plurality of cylinders
including, but not limited to, 2, 3, 4, 5, 6, 8, 10 and 12
cylinders.
A fuel injector (not shown) injects fuel which is combined with the
air as it is drawn into the cylinder 18 through an intake port. The
fuel injector may be an injector associated with an electronic or
mechanical fuel injection system 20, a jet or port of a carburetor
or another system for mixing fuel with intake air. The fuel
injector is controlled to provide a desired air-to-fuel (A/F) ratio
within each cylinder 18.
An intake valve 22 selectively opens and closes to enable the
air/fuel mixture to enter the cylinder 18. The intake valve
position is regulated by an intake cam shaft 24. A piston (not
shown) compresses the air/fuel mixture within the cylinder 18. A
spark plug 26 initiates combustion of the air/fuel mixture, driving
the piston in the cylinder 18. The piston drives a crankshaft (not
shown) to produce drive torque. Combustion exhaust within the
cylinder 18 is forced out an exhaust port when an exhaust valve 28
is in an open position. The exhaust valve position is regulated by
an exhaust cam shaft 30. The exhaust is treated in an exhaust
system and is released to atmosphere. Although single intake and
exhaust valves 22,28 are illustrated, it is appreciated that the
engine 12 can include multiple intake and exhaust valves 22,28 per
cylinder 18.
The engine system 10 can include an intake cam phaser 32 and an
exhaust cam phaser 34 that respectively regulate the rotational
timing of the intake and exhaust cam shafts 24,30. More
specifically, the timing or phase angle of the respective intake
and exhaust cam shafts 24,30 can be retarded or advanced with
respect to each other or with respect to a location of the piston
within the cylinder 18 or crankshaft position. In this manner, the
position of the intake and exhaust valves 22,28 can be regulated
with respect to each other or with respect to a location of the
piston within the cylinder 18. By regulating the position of the
intake valve 22 and the exhaust valve 28, the quantity of air/fuel
mixture ingested into the cylinder 18 and therefore the engine
torque is regulated.
The engine system 10 can also include an exhaust gas recirculation
(EGR) system 36. The EGR system 36 includes an EGR valve 38 that
regulates an exhaust flow back into the intake manifold 14. The EGR
system is generally implemented to regulate emissions. However, the
mass of exhaust air that is recirculated back into the intake
manifold 14 affects engine torque output.
A control module 40 operates the engine based on the engine torque
control of the present invention. More specifically, the control
module 40 generates a throttle control signal based on an engine
torque request (T.sub.REQ) and a throttle position signal generated
by a throttle position sensor (TPS) 42. T.sub.REQ is generated
based on a driver input such as an accelerator pedal position. The
control module commands the throttle to a steady-state position to
achieve an effective throttle area (A.sub.eff). A throttle actuator
(not shown) adjusts the throttle position based on the throttle
control signal. The throttle actuator can include a motor or a
stepper motor, which provides limited and/or coarse control of the
throttle position. The control module 40 also regulates the fuel
injection system 20, the cam shaft phasers 32,34 and the EGR system
36 to achieve T.sub.REQ.
An intake air temperature (IAT) sensor 44 is responsive to a
temperature of the intake air flow and generates an intake air
temperature signal. A mass airflow (MAF) sensor 46 is responsive to
the mass of the intake air flow and generates a MAF signal. A
manifold absolute pressure (MAP) sensor 48 is responsive to the
pressure within the intake manifold 14 and generates a MAP signal.
An engine coolant temperature sensor 50 is responsive to a coolant
temperature and generates an engine temperature signal. An engine
speed sensor 52 is responsive to a rotational speed of the engine
12 and generates in an engine speed signal. Each of the signals
generated by the sensors are received by the control module 40.
The engine torque control system of the present invention
determines A.sub.eff based on a desired manifold absolute pressure
(P.sub.m*). In one embodiment, P.sub.m* is determined considering
the throttle 16 only. In an alternative embodiment, P.sub.m* is
determined considering the throttle 16, the EGR system 36 and the
cam phasers 32,34. When considering the throttle 16 only, the mass
of air into the intake manifold (m.sub.a) can be determined using
the speed density approach according to the following equation:
.eta..times..times. ##EQU00001## where R is the universal gas
constant, V.sub.d is the displacement volume of the engine 12,
.eta..sub.v is the volumetric efficiency of the engine 12 and
T.sub.c is the temperature of the air coming into the intake
manifold 14.
Methods of determining ma are disclosed in commonly assigned U.S.
patent application Ser. No. 10/664,346, filed Sep. 17, 2003 and
entitled Dynamical Torque Control System, and U.S. patent
application Ser. No. 10/463,166, filed Jun. 17, 2003 and entitled
Model Following Torque Control, the disclosures of which are
expressly incorporated herein by reference.
Because m.sub.a is already known, equation (1) can be modified to
calculate the desired MAP (P.sub.m*) according to the following:
.times..eta..times..times. ##EQU00002## The scaled volumetric
efficiency (V.sub.e) of the engine 12 is provided as: .eta..times.
##EQU00003## Merging equation (3) into equation (2) provides:
.times. ##EQU00004## Although V.sub.e can be calculated from
equation (3), V.sub.e is a function of P.sub.m and N.sub.e. In
practice, V.sub.e varies based on several factors including
altitude and temperature. To account for this variance, V.sub.e is
adapted according to the following relationship:
.gamma..times..times. ##EQU00005## where .gamma. is the ratio of
specific heats for air.
In the case where only the throttle 16 is considered, the engine
torque control system of the present invention models V.sub.e as a
function of m.sub.a and N.sub.e. An exemplary model is provided as
follows: V.sub.e=k.sub.0+k.sub.1N.sub.e+k.sub.2m.sub.a (6) where
k.sub.0, k.sub.1 and k.sub.2 are calibration constants. More
specifically, k.sub.0, k.sub.1 and k.sub.2 are determined based on
m.sub.a and N.sub.e from a look-up table stored in memory. The
look-up table is a two-dimensional table that includes calibration
constant values for given engine speed and mass air bands. Each
band ranges between a minimum and maximum value. For example, each
engine speed band includes a minimum engine speed and a maximum
engine speed. The control module 40 selects the calibration
constants of the mass air band and the engine speed band that
correspond to the current m.sub.a and N.sub.e.
When considering the throttle 16, the EGR system 36 and the cam
phasers 32,34, P.sub.m* is determined according to the following
equation: .times. ##EQU00006## where m.sub.egr is the mass of air
recirculated by the EGR system and V.sub.e is a function of
P.sub.m, N.sub.e, .phi..sub.i and .phi..sub.e. .phi..sub.i and
.phi..sub.e are determined by the control module 40 based on the
cam phaser positions. In this case, the engine torque control
system of the present invention models V.sub.e as a function of
m.sub.a, N.sub.e, .phi..sub.i and .phi..sub.e. An exemplary model
is provided as follows:
V.sub.e=k.sub.o+k.sub.1N.sub.e+k.sub.2m.sub.a+k.sub.3.phi..sub.i+k.sub.4.-
phi..sub.e (8) where k.sub.0, k.sub.1, k.sub.2, k.sub.3 and k.sub.4
are calibration constants. More specifically, k.sub.0, k.sub.1,
k.sub.2, k.sub.3 and k.sub.4 are determined based on m.sub.a,
N.sub.e, .phi..sub.i and .phi..sub.e from a look-up table stored in
memory. The look-up table is a multi-dimensional table that is
developed similarly as described above with regard to equation
(6).
Having determined P.sub.m* as described above, the engine torque
control system determines A.sub.eff according to the following
equation: .times..PHI. ##EQU00007## where .PHI. is based on a
pressure ratio (P.sub.R) according to the following relationships:
.PHI..times..gamma..gamma..times..gamma..gamma..times..times.>.gamma..-
gamma..gamma..gamma..times. .gamma.
.gamma..gamma..times..times..ltoreq. ##EQU00008## where P.sub.R is
the ratio of P.sub.m* to the ambient pressure (P.sub.amb) and
P.sub.critical. P.sub.critical is defined as the pressure ratio at
which the velocity of the air flowing past the throttle equals the
velocity of sound. This condition is called choked or critical
flow. The critical pressure ratio is determined by
.gamma..gamma..gamma. ##EQU00009## where .gamma.=the ratio of
specific heats for air and range from about 1.3 to about 1.4.
The engine torque control system determines the value of P.sub.m*
to produce the desired airflow at the throttle 16. The airflow
enables the correct amount of air to enter the cylinders 18 to
provide T.sub.REQ from the engine 12. Because the control module
commands the throttle to a steady-state position, it can be assumed
that {dot over (m)}.sub.th is equal to m.sub.a. More specifically,
during steady-state the flow across the throttle ({dot over
(m)}.sub.th) is equal to the flow into the cylinders (out of the
manifold) ({dot over (m)}.sub.a). Since A.sub.eff and P.sub.m* are
setpoint targets and time is required to reach these values (e.g.,
approximately 100 ms), it can be approximated that {dot over
(m)}.sub.th is equal to {dot over (m)}.sub.a.
Referring now to FIG. 2, the steps performed by the engine torque
control system will be described in detail. In step 200, control
determines whether T.sub.REQ has been generated. If T.sub.REQ has
not been generated, control loops back to step 200. If T.sub.REQ
has been generated, control determines m.sub.a and {dot over
(m)}.sub.a required to achieve T.sub.REQ in step 202. In step 204,
control calculates V.sub.e based on m.sub.a, N.sub.e or m.sub.a,
N.sub.e, .phi..sub.i and .phi..sub.e. Control determines P.sub.m*
based on ma and V.sub.e in step 206. In step 208, control
determines A.sub.eff based on P.sub.m.* Control regulates the
throttle to achieve A.sub.eff in step 210 and loops back to step
200.
Those skilled in the art can now appreciate from the foregoing
description that the broad teachings of the present invention can
be implemented in a variety of forms. Therefore, while this
invention has been described in connection with particular examples
thereof, the true scope of the invention should not be so limited
since other modifications will become apparent to the skilled
practitioner upon a study of the drawings, the specification and
the following claims.
* * * * *